I remember reading Mad Magazine here and there in my youth, but I connected more with National Lampoon, since I went to high school during the 1970s. Its humor was a little sicker and grosser — hey, I was, like, a teenager. But one thing I do remember from Mad were the cool fold-ins where a picture looked like one thing, until you folded one third of it over to meet the first third, covering the middle — thus showing off the joke.
That all came back today when the New York Times wrote about Al Jaffee, who has drawn the feature since 1964. The online version of the article has a cool Flash graphic showing some classic fold-ins. (Tip of the hat to my colleague Steve Mullis for alerting me to this).